Mississippi’s Thad Cochran was first elected to Congress in 1972. Kansas’ Pat Roberts won his first seat in 1980.

Cochran is 76. Roberts is 78.

Cochran is fighting for his political life after failing to win 50 percent of the vote in Tuesday’s GOP primary against a tea party conservative.

Roberts? He faces a tea partier, too, in Kansas’ August GOP primary.

But while Cochran now ranks as the underdog in an upcoming runoff election this month, Roberts has, well, yet to break a sweat — not that he’ll ever admit it.

Why the difference? Let’s count the reasons.

Cochran ranks as one of the great pork-barrel lawmakers in history, regularly shuttling millions of dollars back to his home state, which ranks as one of the nation’s poorest.

But Cochran’s connection to pork is now out of style with tea party voters, who populate primaries and favor limited government. It’s made him vulnerable.

So has Cochran’s low-key, courtly style.

“Name one fight that Sen. Thad Cochran has led against President Barack Obama,” Cochran opponent Chris McDaniel crowed last week.

Roberts doesn’t lead any parades either. But he’s not shy about regularly, and vociferously, expressing his outrage at Obama.

“I could go on and on about the lack of accountability in the Obama administration,” Roberts said in Wichita. “Obamacare, the VA, the IRS, Benghazi … it’s really just shameful.”

Although Roberts has brought his share of pork home, he’s not in Cochran’s league.

Years ago, Roberts foresaw the coming conservative wave and tilted right. He correctly viewed his biggest weakness as a challenge from a tea party type.

Last year, Roberts ranked as the eighth-most conservative senator, according to the National Journal. Cochran, also facing re-election in 2014, clocked in at 34th.

McDaniel is far better equipped to challenge a legacy politician such as Cochran than Milton Wolf, the man running against Roberts. McDaniel is described as akin to a Southern preacher who, the National Review said, works his audience in a call-and-response style found in some churches.

Wolf’s campaign is stuck on a single note, which is that Roberts is out of touch with Kansas because he’s lived out East so long.

Two longtime senators. Two tea party challenges. Two seemingly different results. The caveat: Wolf still has two months to turn it around.